Abstract This paper presents a sustainable PCM for potential applications in thermal energy storage in buildings. Up to date, PCMs are elaborated with raw and expensive materials. Therefore, the main appeal of the PCM is its support material, recycled diatomite, a palm oil industrial waste. PCMs were elaborated with three support materials (raw, recycled, and recycled-calcined diatomite) to compare its influence on PCM thermal and chemical behavior. Different mixtures of organic components (esters of palm oil and commercial stearic acid in different proportions) were incorporated into the three support materials. A characterization process by differential scanning calorimetry (DSC) was used to select the organic mixture with the highest value of latent heat of fusion and the closest phase change temperature range to the thermal comfort in each support material. To establish the thermal and chemical stability of the PCMs, DSC, thermogravimetry (TGA), and Fourier-transform infrared spectroscopy (FT-IR) analysis were carried out at 0, 120, 240 and 360 thermal cycles. One of the major outcomes from these joint efforts is the good and long thermal and chemical performance of the PCMs composed by 100% of commercial stearic acid methyl esters and recycled-calcined diatomite. This PCM is capable to have a similar energy storage capacity to the PCM supported in raw diatomite. The results show the effectiveness of the use of recycled-calcined diatomite as support material to obtain potential and sustainable PCMs for energy saving.